A text-book of physiology for medical students and physicians . ,The Croonian Lectures on The Chemical Side of Nervous Activity, Mosso, .Die Temperatur des Gehirns, 1894. 138 PHYSIOLOGY OF CENTRAL NERVOUS SYSTEM. delicate thermometer could be inserted so as to lie in contact withbrain. So also the facts briefly mentioned in regard to the Nisslgranules give some corroborative evidence that the activity ofthe nervous system is accompanied by and probably caused bya chemical change within the cells, since the excessive activity ofthe nerve cells seems to be accompanied by some change in th
A text-book of physiology for medical students and physicians . ,The Croonian Lectures on The Chemical Side of Nervous Activity, Mosso, .Die Temperatur des Gehirns, 1894. 138 PHYSIOLOGY OF CENTRAL NERVOUS SYSTEM. delicate thermometer could be inserted so as to lie in contact withbrain. So also the facts briefly mentioned in regard to the Nisslgranules give some corroborative evidence that the activity ofthe nervous system is accompanied by and probably caused bya chemical change within the cells, since the excessive activity ofthe nerve cells seems to be accompanied by some change in thesegranules, and in abnormal conditions associated with loss of func-tional activity the granules undergo chromatolysis,—that is, theyare disintegrated and dissolved. Obvious histological changes whichimply, of course, a change in chemical structure, have been observedby a number of investigators.* All seem to agree that activity ofthe tissue, whether normal or induced by artificial stimulation,may cause visible changes in the appearance of the cell and its. Fig. 65.—Spinal ganglion cells from English sparrows, to show the daily variation inthe appearance of the cells due to normal activity: A. Appearance of cells at the end ofan active day; B, appearance of cells in the morning after a nights rest. The cytoplasmis filled with clear, lenticular masses, which are much more evident in the rested cells thai;in those fatigued.—(Hodge.) nucleus. Activity within normal limits may cause an increase inthe size of the cell together with a diminution in the stainable(Nissl) substance, and excessive activity a diminution in size of thecell and the nucleus, the formation of vacuoles in the cell body,and a marked effect upon the stainable material. Hodge hasshown that in birds, for instance, the spinal ganglion cells of aswallow killed at nightfall after a day of activity exhibit a markedloss of substance as compared with similar cells from an animalkilled in the early morning (Fig. 6
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